Art of M C Escher

M. C. Escher (1898 〜 1972) is a Dutch artist whose works are strongly mathematical.
Some are mathematical images of tilings, recursion, infinity, reflection, geometric process.
Others illustrate the concepts of the above.
While still others exploit illusion and human perception to illustrate the above subjects.

One of my favorite piece by Escher. Called 4-color butterfly. Note the interlinking circles, orthogonal to each other, while for each butterfly the colors are distributed symmetrically.